Effects of litter and plant roots on soil properties and infiltration capacity with vegetation succession on the Loess Plateau, China

<p><strong>Abstract: </strong>Vegetation restoration significantly affect soil infiltration capacity, surface runoff and soil erosion by substantially improving vegetation structure and soil properties. However, changes in soil properties and infiltration capacity at different stages of secondary succession in forestland on the Loess Plateau need to be further understood. The aim of this study was to quantify the effects of stand types at different succession stages on soil properties and infiltration capacity, and to identify key factors influencing soil infiltration characteristics on the Loess Plateau, so as to serve for soil erosion control, land use optimization and watershed management. Here, we selected four tree successional stages, consisting of <em>Betula platyphylla</em>&#160;Suk.(Bp), <em>Pinus tabulaeformis</em>&#160;Carr.(Pt), <em>Quercus wutaishanica </em>Suk<em>- Pine tabulaeformis</em>&#160;Carr mixed forests (Qw-Ptmf), and <em>Quercus wutaishanica</em>&#160;Mary(Qw), and sloping farmland as controls, to analyse changes in litter and plant roots characteristics, corresponding soil properties and infiltration characteristics. Soil hydraulic conductivity was measured using the single-ring-knife constant water head infiltration method. Soil properties were determined and the effect of soil properties on soil infiltration capacity was analyzed using path analysis. The results showed that litter thickness and biomass generally tended to increase with vegetation succession. Among them Qw-Ptmf had the greatest litter biomass and fine root biomass. Root biomass was greater in all stand types in the 0-5 cm and 5-20 cm soil layers than in the 20-40 cm, with the most rapid decline from the 0-5 cm to the 5-20 cm soil layer. The continuous vegetation restoration significantly improved soil properties and infiltration capacity compared to the control farmland. Qw-Ptmf showed the best soil properties and infiltration capacity, followed by Qw, Pt&#160;and Bp. Soil properties of the same tree species at different ages were different, and generally tend to get better as succession progresses. Path analysis showed that litter and plant roots together improved soil properties in the 0-5 cm soil layer, while below 0-5 cm plant roots dominated. Soil porosity and soil bulk density were the most critical factors influencing soil infiltration capacity.&#160;It is helpful to understand&#160;that vegetation succession&#160;fundamentally reduces surface runoff and soil erosion by improving soil properties (especially from 0-20 cm) and increasing soil infiltration capacity in the area. Underground plant roots and&#160;ground litter coverage play an important role in improving positively soil properties and thus&#160;soil infiltration capacity&#160;with vegetation succession. Results of this study can be useful for regional ecological restoration planning, stand management and soil erosion prediction on the Loess Plateau.</p> <p><strong>Keywords</strong><strong>:</strong>&#160;Forestland &#160;litter and plant roots &#160;soil properties &#160;infiltration capacity &#160;vegetation succession &#160;Loess Plateau</p>